1. Field of the Invention
The present invention relates to non-impact printing apparatus for recording on a moving recording medium.
2. Brief Description of the Prior Art
In the prior art as exemplified by U.S. patent application Ser. No. 132,638, filed Dec. 9, 1987, which is a continuation of U.S. patent application Ser. No. 033,550, filed Apr. 1, 1987, both now abandoned, printing apparatus is described which comprises a multiplicity of individually addressable and energizable point-like radiation sources, such as light-emitting diodes (LED's), arranged in a row(s) for exposing points upon a photoreceptor during movement thereof relative to and in a direction normal to the row(s). Driver circuits are provided for simultaneously energizing the radiation sources responsive to respective data bit input signals applied to the driver circuits during an information line period. The print or recording head includes a support upon which are mounted chips placed end to end and upon each of which are located a group of LED's. The driver circuits are incorporated in other chips located to each side of the linear array of LED chips. The driver circuits in this apparatus each include a shift register for serially receiving data-bit signals and for driving respective LED's in accordance with the data or image signals.
The shift registers on adjacent chips are coupled together to function as a single "shift register assemblage" so that the data bits (mage signals) flow down and fill the shift registers in the shift register assemblage bit by bit under clock control. As driver chips are provided to both sides of the LED's and the drive circuitry to the LED's is alternately interleaved, data must be provided to the shift registers located to one side of the LED's, as appropriate for the odd-numbered LED's, and similarly to the shift registers on the other side the data is provided to the shift registers controlling the even-numbered LED's.
In order to speed up the flow of data to the shift registers it is known not only to feed the odd and even data bits simultaneously to respective shift register assemblages, but to also divide the feeding of data to two shift register assemblages on the same side of the LED's so that while data is being shifted down one set of shift registers of say the odd bits, additional odd bits of data simultaneously are being shifted down other shift register assemblages.
The data management for this type of apparatus may be complex or simple depending upon the arrangement of the data. Where the data is outputted by a raster image processor (RIP) that is suited for use with a laser beam, data management for distributing this data for use with a multiple array print head may present those difficulties. This is due to the consecutive sequential order in which data is provided for a laser exposure device that employs, say, a rotating polygon to expose a line in the mainscanning direction, first pixel first, and so on until the last pixel on that line is exposed. As used herein, the term "consecutive sequential order" refers to an order of data that is congruous with the order of the data as it is to appear on the recording medium.
Data management is made particularly difficult where it is desired to provide a single buffer memory chip for storing a single line of data prior to feeding this data to the shift registers on the print head.
It is, therefore, an object of the invention to provide printer apparatus with improved circuitry for formatting data.